Longest Main Street in the World (Highway 83, through Rio Grande Valley)

Highway 83 through the Rio Grande Valley has been described as “the longest main street in the world” since at least 1929. It continues about 100 miles from Rio Grande City until the highway ends at Brownsville.
 
         
Wikipedia: U.S. Route 83
U.S. Highway 83 is one of the longest north-south U.S. Highways in the United States, at 1885 miles. Only three other north-south routes are longer: U.S. 1, U.S. 41 and U.S. 87. The highway’s northern terminus is north of Westhope, North Dakota, at the Canadian border, where it continues as Manitoba Highway 83. The southern terminus is in Brownsville, Texas, at the Veteran’s International Bridge on the Mexican border, connecting with Mexican Federal Highway 180. 
   
Route description
Texas
US 83’s southern terminus is at a junction with US 77 on the southern end of Brownsville. It remains co-signed with US 77 until Harlingen, where US 77 makes a sharp turn northward and US 83 maintains a westerly route. From here, the highway roughly parallels the Rio Grande until Laredo where it makes a northwesterly turn. Merging with I-35 just south of downtown, US 83 remains co-signed with the interstate until an exit at Botines, Texas. From there, it continues northward, intersecting with I-10 just south of Junction. US 83 is co-signed with I-10 for approximately 8 miles, turning northward and leaving I-10 at the Kimble County Airport.
 
After continuing northward through several rural western Texas towns, US 83 then merges with US 84 east of Tuscola, where it makes a sharp turn back to the north. US 83/84 remains a co-signed route until Abilene, where US 84 turns to the northwest and US 83 remains northbound, merging with US 277 on the west side of the city. US 83/277 remains a co-signed route until approximately 2 miles north of Anson, where US 277 turns northeast, and US 83, northwest.
 
After merging with US 380 in Aspermont and briefly sharing a route, US 83 continues northward, merging with US 62 in Paducah. US 83/62 continues as a co-signed route until approximately 15 miles south of Wellington, where US 62 makes a sharp turn eastward, leaving US 83 to continue northward, where it crosses into Oklahoma approximately 6 miles north of Perryton.
 
Handbook of Texas Online
HIDALGO COUNTY. Hidalgo County (T-16), in South Texas, is bordered by Cameron County on the east, Brooks County on the north, Starr County on the west, and Mexico on the south.
(...)
Thriving towns sprang up across the southern part of the county east to west along U.S. Highway 83, which by 1930 was described as the “longest main street in the world.” 
     
30 January 1929, Appleton (WI) Post-Crescent, pg. 7, col. 6 ad:
“The Sunshine Spends Its Winters Along the Rio Grande.
WHY DON’T YOU?”
In the magic land of the Valley of the Lower Rio Grande, dreams of boundless wealth are coming true. Where cactus grew in 1911, stands today the “City of Palms” McAllen, a town of 14,000 people, with 20 miles of paved streets—on the “Longest Main Street in the world,” extending from Brownsville on the Gulf to the shores of the Rio Grande and Old Mexico on the West.
 
1 January 1930, Brownsville (TX) Herald, pg. 7, col. 5:
A lengthy parade of automobiles bearing fans to the portals of Tucker field formed on the “longest Main street” Wednesday morning and continued to roll until noon.
   
9 March 1930, Brownsville (TX) Herald, pg. 3, col. 5:
Paved roads were next, and the strip known as the “Longest Main Street in the World” was built, linking the extreme ends of the Valley with paving unsurpassed in the nation.
   
20 May 1931, San Antonio (TX) Express, pg. 11, col. 8 ad:
Have you traveled down the “longest main street in the world”—have you plunged into the surf at Boca Chica—have you seen the Rio Grande by moonlight—have you felt the romantic charm of Matamoros, in Old Mexico?
(...)
Brownsville
 
23 December 1939, El Paso (TX) Herald-Post, “Lower Rio Grande Valley is Little World All To Itself” by Ernie Pyle, pg. 3, cols. 2-3:
A main highway runs from one end of the Valley to the other. You are scarcely through one town before you are in another. They call it the longest Main Street in the world. 
 
25 November 1952, Valley Morning Star (Harlingen, TX), “Hidalgo County Centennial Script Feature Early Days,” pg. 5, col. 2:
Longest main street in the world—A salute to Highway 83.
   
13 October 1953, Valley Morning Star (Harlingen, TX), pg. 2, col. 5:
“The Valley can get plenty of national publicity out of the president’s journey down the ‘longest main street in the world’—especially if the longest main street is lined with the Valley school children,” he said.
   
17 October 1953, Corpus Christi (TX) Times, pg. 1, col. 8:
They will drive slowly through nine towns on U.S. Highway 83, which Valley boosters like to call “the longest main street in the United States.”
       
27 December 1953, Dallas (TX) Morning News, “Valley Magic Erases Big Freeze Tragedy,” part 4, pg. 1, col. 1:
Along a 40-mile strip of Texas roadway that has been called the longest Main Street in the world, there was a strange preoccupation last week. 
 
21 October 1955, Corpus Christi (TX) Caller-Times, pg. 11F, col. 2:
Highway 83 from Rio Grande City to Brownsville—some 100 miles—is talked about in the Valley as the “longest main street in the world.”
 
26 May 1957, Oakland (CA) Tribune, “Texas vacationists saw ‘shrimp boats a-comin’,’ explored Rio Grande Valley,” Parade magazine,  pg. 26, col. 4:
They wound up their vacation by “exploring” the southern end of the Rio Grande Valley, traveling the “longest Main Street in America”—a 70-mile stretch of palm-lined highway from Mission to Brownsville.